1. Field of the Invention
The present invention relates to wireless communication and, more particularly, to a method for carrying out synchronization tracking and a wireless device using the same.
2. Related Art
3rd generation partnership project (3GPP) long term evolution (LTE) is an improved version of a universal mobile telecommunication system (UMTS) and is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. The 3GPP LTE adopts MIMO (multiple input multiple output) having maximum four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) that is an evolution of the 3GPP LTE.
As disclosed in 3GPP TS 36.211 V8.7.0 (2009-May) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)”, a physical channel in 3GPP LTE/LTE-A may be divided into PDSCH (Physical Downlink Shared Channel) and PDCCH (Physical Downlink Control Channel) being a downlink channel, and PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel) being an uplink channel.
Synchronization is a basic procedure for the communication between the BS and the terminal are the basic steps. In general, the terminal performs the initial synchronization through a synchronization signal. Next, the terminal performs synchronization tracking to maintain the synchronization. If the terminal does not maintain the synchronization longer, the terminal moves to another cell or declares wireless link failure.
An existing 3GPP LTE provides a cell-specific reference signal (CRS) for synchronization tracking. However, a following approach is discussed. Since the CRS is transmitted all sub-frames across the entire system bandwidth, the CRS is not transmitted or the CRS is transmitted with limited resources in order to reduce overhead.